Nd:YAG lasers operating at 1.06 .mu.m wavelength are very well known. These lasers have been deployed in a wide range of applications.
More recently, there has been considerable interest in lasers operating with output around 1.5 .mu.m wavelength, because the eye is far less susceptible to damage at this wavelength. These lasers are often referred to as eyesafe lasers, and generally they are either based on Erbium doped glass or YAG (operating fundamentally at around 1.5 .mu.m), or rely on parametric or other conversion from a different fundamental wavelength. For example, eyesafe lasers based upon Nd:YAG lasers and conversion from 1.06 to 1.5 .mu.m by Raman or OPO (optical parametric oscillator) are known.
Many sensors in military and other applications operate only at 1.06 .mu.m, and replacement of the laser source is inhibited by the prohibitive cost of replacing all sensors. For example, laser guided weapons exist in large stockpiles with systems configured for 1.06 .mu.m. However, the operational platforms which designate targets for these weapons require eyesafe lasers for new applications. Often there are space, eight, and maintenance considerations mitigating against proliferation of laser sources on forward-deployed platforms. Nevertheless, systems are now being provided with separate lasers for different parts of the system, for example 1.06 .mu.m lasers for the laser designator components, and 1.51 .mu.m lasers for the range finders.